php_new_syntax.md

PHP 7.0

• Scalar type declarations: Allows functions to require certain types of arguments.

  function sum(int $a, int $b) {
      return $a + $b;
  }

• Return type declarations: Allows functions to declare the type of the return value.

  function sum($a, $b): int {
      return $a + $b;
  }

• Null coalescing operator (??): Returns its first operand if it exists and is not NULL; otherwise it returns its second operand.

  $username = $_GET['user'] ?? 'nobody';

• Spaceship operator (<=>): A three-way comparison operator. It returns -1, 0 or 1 when $a is respectively less than, equal to, or greater than $b.

  echo 1 <=> 2;  // outputs -1

• Constant arrays using define(): Defines an array as a constant.

  define('ANIMALS', ['dog', 'cat', 'bird']);

PHP 7.1

• Nullable types: Allows a type to be either a specified type or NULL.

  function test(?string $name) {
      var_dump($name);
  }
  test(null);  // outputs NULL

• Void functions: Specifies that a function should not return a value.

  function test(): void {
      echo 'Hello, World!';
  }

PHP 7.2

• Object type: Allows for functions to accept any object as a parameter, or to return an object.

  function test(object $obj): object {
      return new SplQueue();
  }

PHP 7.3

• Flexible Heredoc and Nowdoc Syntaxes: Allows for indenting of closing markers.

  echo <<<END
      A indented heredoc syntax example.
  END;

PHP 7.4

• Typed Properties: Declares the type of a class property.

  class User {
      public int $id;
      public string $name;
  }

• Arrow Functions: Allows for cleaner one-liner functions with implicit variable scope.

  $factor = 10;
  $nums = array_map(fn($n) => $n * $factor, [1, 2, 3, 4]);

• Null coalescing assignment operator (??=): It's a shorthand for the common case of needing to use a ternary in conjunction with isset().

  $data['date'] ??= '2023-01-01';

PHP 8.0

• Named arguments: Allows passing arguments to a function based on the parameter name, instead of the parameter position.

  htmlspecialchars($string, double_encode: false);

• Constructor Property Promotion: Combines class properties and constructor parameters.

  class Point {
      public function __construct(
          public float $x = 0.0,
          public float $y = 0.0,
          public float $z = 0.0,
      ) {}
  }

• Match expression: A switch-like expression that can return values.

  echo match (1) {
      0 => 'zero',
      1 => 'one',
      default => 'more',
  };

• Nullsafe Operator (?->): Allows for the chaining of method calls and property accesses even if one of the elements in the chain returns null.

  $country = $session?->user?->getAddress()?->country;

• Attributes (Annotations): Provides a way to add metadata to classes, methods, properties, parameters, and constants.

  #[ExampleAttribute]
  public function hello() {}

• Union types: Allows a function to require arguments or return values of multiple types.

  class Number {
      private int|float $number;
  }